Monday, December 1, 2014

Installing a Pilot-Mounted Coupler on a Brass Steam Locomotive, Part 2

Thanks again to those commenting on Part 1 of this series. I took your comments to heart - and promptly chickened out. I'm going to wait a bit before attempt to drill such a small hole in the (very) narrow shank of a KD #58 metal coupler, drill press or no drill press.

To my credit - or at least an argument against my "chicken-ness" - I found an alternative solution. McHenry makes a plastic coupler that has a much-more-reliable closing mechanism: metal spring rather than a sliver of plastic. There's even a little letter "E" pressed into the underside of the shank that you can use to start your hole (with the point of a safety pin, in my case) and then it's a snap (not literally, thankfully) to drill out the hole with a #72 bit.

There're only two problems:

  1. The couplers are oversized - but BillS told me at my last operating session on Friday (report coming soon) that they make a "scale" size coupler. So this won't be a problem for long.
  2. The coupler shank is much thinner than the draft gear box, resulting in some drooping...

Droopy McHenry Coupler
The solution was easy to figure, but a little more difficult to do. I basically had to "thicken" the coupler shank using two bits of scale 1x6 styrene strip. Since I wanted everything to continue to move nice and easily, I had to - yup, you guessed it - drill some more holes. I recommend you mark/drill the hole first then cut the length to fit. Ask me how I know....

Teeny Tiny Coupler Shim
The resulting shims (one pictured above) are so small, I couldn't even get my camera to focus properly for a picture (note to self: get a macro lens app). But I used some copper wire to thread a shim, then the coupler, then another shim into a "sandwich" (shank between two shim "slices") and then used just the tiniest amount of styrene glue you can imagine to stick things together just long enough to keep the 3 holes lined up for positioning in the pilot draft gear box and sliding the fixing pin down from the top and through the holes.

It actually took me much longer to type that out than it did to do. The result was certainly worth it:

Non-droopy coupler
I'm very happy with how this turned out, and the coupler performed like a champ at the ops session. Pilot couplers on brass steamers are usually just dummies, but if your engine is in anything but dedicated passenger service, it's likely it's going to have to switch a car or two at some point using the pilot. On a local freight engine like my K-1 mogul, a working front coupler is an absolute must. And now I have a pretty easy way of modifying couplers to fit what the brass manufacturer left me with. Hope you find this method helpful too.

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